Allowance for Credit Losses and Reserve for Unfunded Lending Commitments - Charge-Offs (Details) $ in Millions	9 Months Ended
Sep. 30, 2024 USD ($)
Financing Receivable, Credit Quality Indicator [Line Items]
2024	$ 71
2023	474
2022	681
2021	493
2020	200
Prior	182
Total Term Loans	2,101
Revolving Loans	7,865
Revolving Loans Converted to Term	95
Total	10,061
Credit Card:
Financing Receivable, Credit Quality Indicator [Line Items]
Revolving Loans	7,798
Revolving Loans Converted to Term	94
Total	7,892
Credit Card: \| Domestic Card
Financing Receivable, Credit Quality Indicator [Line Items]
Revolving Loans	7,425
Revolving Loans Converted to Term	84
Total	7,509
Credit Card: \| International card businesses
Financing Receivable, Credit Quality Indicator [Line Items]
Revolving Loans	373
Revolving Loans Converted to Term	10
Total	383
Consumer Banking:
Financing Receivable, Credit Quality Indicator [Line Items]
2024	71
2023	474
2022	630
2021	457
2020	184
Prior	129
Total Term Loans	1,945
Revolving Loans	57
Revolving Loans Converted to Term	1
Total	2,003
Consumer Banking: \| Auto
Financing Receivable, Credit Quality Indicator [Line Items]
2024	70
2023	474
2022	630
2021	457
2020	184
Prior	126
Total Term Loans	1,941
Revolving Loans	0
Revolving Loans Converted to Term	0
Total	1,941
Consumer Banking: \| Retail banking
Financing Receivable, Credit Quality Indicator [Line Items]
2024	1
2023	0
2022	0
2021	0
2020	0
Prior	3
Total Term Loans	4
Revolving Loans	57
Revolving Loans Converted to Term	1
Total	62
Commercial Banking:
Financing Receivable, Credit Quality Indicator [Line Items]
2024	0
2023	0
2022	51
2021	36
2020	16
Prior	53
Total Term Loans	156
Revolving Loans	10
Revolving Loans Converted to Term	0
Total	166
Commercial Banking: \| Commercial and multifamily real estate
Financing Receivable, Credit Quality Indicator [Line Items]
2024	0
2023	0
2022	5
2021	31
2020	0
Prior	49
Total Term Loans	85
Revolving Loans	0
Revolving Loans Converted to Term	0
Total	85
Commercial Banking: \| Commercial and industrial
Financing Receivable, Credit Quality Indicator [Line Items]
2024	0
2023	0
2022	46
2021	5
2020	16
Prior	4
Total Term Loans	71
Revolving Loans	10
Revolving Loans Converted to Term	0
Total	$ 81

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